Small firms are waiting six weeks longer than big businesses for invoices to be paid, a study shows.

The delay is placing huge pressure on their cashflow as well as their ability to expand, said the Asset Based Finance Association (ABFA).

The average waiting time for payment is 71 days for smaller firms compared with 38 days for the largest companies.

Jeff Longhurst, chief executive of ABFA, said: "Whilst big businesses are enjoying more prompt payment, small and medium sized enterprises are suffering more than ever.

"The delays which became common during the credit crunch have quite clearly persisted, despite the wider economic recovery.

"The impact of delayed payment on businesses' cashflow and capacity to expand order books presents a serious concern, particularly for smaller companies. Even when a business is thriving, just a few unpaid invoices can end up a real threat to survival.

"As well as paying invoices late, many companies are imposing extended payment terms on their suppliers from the outset, which can end up having a similar impact."

The report warned that the "upheaval" of the European Union referendum result to lead to further delays.